1. Field of the Invention
The invention relates to a control equipment for an industrial sewing machine, it being possible, via switchgears such as switches, probes, sensors or the like, to switch on or off functions and connection states by a certain voltage level being applied to an input circuit of the control in order to generate a certain connection state.
2. Background Art
In the field of industrial sewing machines, voltage levels in the form of the electric potentials 0 V, +5 V, +24 V are defined as connection levels. Depending on the type of sewing machine, the sewing machine manufacturer, the use and wiring, switchgears are used, which work with the mentioned varying connection levels. In known control equipments, differing input circuits and circuit dimensionings are required by the varying connection levels. With input circuits of the type under regard, it is known to modify the connection levels for the activation of the input circuit by the program-controlled connection of certain circuit elements, so-called pull-up or pull-down resistors, the known circuits however having the drawback that the input circuit is only activated when a single defined connection level is applied. As a result, varying controls for almost identical requirements must be made available during the manufacture of controls for different types of sewing machines or fields of application, because the connection levels for the individual switchgears are differently defined.
U.S. Pat. No. 4,837,672 describes a control circuit being able to produce a supplying voltage starting from different input voltages, i.e. 100 V or 220 V.
U.S. Pat. No. 4,236,103 teaches a corresponding power supply for a sewing machine.
U.S. Pat. No. 6,027,029 describes a smart card as an example for a control card converting a program voltage. This conversion only takes places, as long as this program voltage is under a certain threshold level. If this is verified, input voltages are converted to first and second voltages of a given level. These levels act as a single level voltage pair having a switching level in-between.
U.S. Pat. No. 5,865,134 describes another example for a control card.
U.S. Pat. No. 4,602,581 and U.S. Pat. No. 5,008,601 disclose the usage of an A/D-converter for a speed control of a sewing machine.